An electro-optical apparatus particularly suitable for exposing a sample of light sensitive material to provide a graded series of exposures of different intensity levels. The apparatus includes a light source, beam shaping optics, and a rotatable polarizer. The light source provides a Gaussian beam of light directed along an optical axis. The beam shaping optics are disposed in the optical path and are adapted to expand the Gaussian beam of light into an elongated beam of light and to project the elongated beam of light along the optical axis toward a sample. The rotatable polarizer, disposed in the optical path intermediate the light source and the beam shaping optics, is rotated to vary the intensity level of the beam of light.